Wouldn't it be easy enough to modify a cheap extension tube (like this one on eBay) so that a osciliscope could be hooked up to the Vbat and A_GND contact to see exactly what voltage is driving the AF system for a given camera?

That might not tell you what's going on downstream between the AF electronics and the USM motor, but it might help to support the higher-voltage/faster-AF theory. If the voltages for a 7.4V-based camera and an 11.2V-based camera are the same, then that theory can be put to bed.

Wouldn't it be easy enough to modify a cheap extension tube (like this one on eBay) so that a osciliscope could be hooked up to the Vbat and A_GND contact to see exactly what voltage is driving the AF system for a given camera?

That might not tell you what's going on downstream between the AF electronics and the USM motor, but it might help to support the higher-voltage/faster-AF theory. If the voltages for a 7.4V-based camera and an 11.2V-based camera are the same, then that theory can be put to bed.

Actually, after reading the nth post claiming "a higher voltage may likely drive the AF motor faster", "maybe Canon will develop higher voltage batteries..." "it seems there's still someone who doesn't get that a higher voltage..." and things like those, I gave up replying. But look at the figure above: Vbat and A_GND is the power line which feeds the lens' motors, and it's +6/-6 Volts in any camera. VDD and D_GND is the power line that feeds the logic, and it's +5.5/-5.5 Volts in any camera. You can check it yourself, no need for an oscilloscope, just use a Voltmeter on your camera, the red terminal on Vbat and the black one on A_GND. Note that the large contact A_GND on the lens corresponds to 2 contacts on the camera, pick any of them: you'll read 6 Volts.

By the way, Chuck Westfall NEVER said the 1D X focuses faster than the 5D III because the battery has a higher voltage, he said it's because it's more poweful, and, indeed, it is. Roughly 4 W more than dual LP-E6.

I think I'll start another thread on this matter in the near future, it seems so many are interested, and it also seems there's a lot of misconception regarding this.

Neuro, I'm not mentioning voltage at all, instead I said 'current'. I think the two batteries in the grip are not 'used' in an alternate sequence, they are used simultaneously. Actually, inserting two discharged batteries, both incapable of even letting you switch the camera 'on' when used alone, will let you switch the camera 'on' and even shoot photos. It's the shutter count per battery that is calculated in an alternate sequence, being not possible to show 1/2 increments per battery, which would be nonsense. They are connected in parallel, so the voltage is the same, but are capable of delivering double the current of a single battery

Makes sense. However, empirically the single battery of a 1-series does drive the lens AF motor faster than the pair of batteries used in a grip. This is evident when a 'slow focusing' lens like the 85L II (where the focusing group movement is visible and slow enough to be easily seen) is focused from MFD to infinity on the 1D X vs. a gripped 7D, with fresh batteries. I'm not sure about the electronic basis for the difference in AF speed (current draw or firmware), but the difference is there.

All the top-end Canon lenses use ultrasonic motors. These are not like normal electric motors where the higher voltage you feed them, the faster they go. The speed depends on the frequency and phasing of the drive signals, and that is generated by the lens microcontroller from a quartz frequency source, it won't change with supply voltage. The only way that the grip would allow faster focus is if the firmware was deliberately slowing down the focus to preserve battery power. That is possible, it might be a bad thing if the camera gets a reputation for low battery life. That's what Nikon is doing - the speed restrictions without grip are entirely firmware. Canon has thankfully been free of that kind of silly marketing ploy, I hope that they don't start now.

I guess Chuck Westfall of Canon got it wrong according to you. He says the higher voltage is the reason but maybe you are right.

I see two big ways that the 7D2 and 70D can distinguish themselves from the Rebel line. One is sensor and the other is focus. If you look at the 7D and the 60D, there are a few minor differences between cameras, but only two big diferences. The 7D has way beter focusing and the 60D has the articulating screen.

I would not be surprised to see new sensors in both. I would expect to see touchscreens, wifi, and GPS in both. I expect the difference to be significantly better AF and a higher frame rate in the 7D, with a few minor improvements... I would also expect NO articulated screen in the 7D2.

Time will tell. I have no intentions of getting a 70D, but since it's features will give a good clue to the 7D2, I eagerly await it's announcement.

I see two big ways that the 7D2 and 70D can distinguish themselves from the Rebel line. One is sensor and the other is focus. If you look at the 7D and the 60D, there are a few minor differences between cameras, but only two big diferences. The 7D has way beter focusing and the 60D has the articulating screen.

I would not be surprised to see new sensors in both. I would expect to see touchscreens, wifi, and GPS in both. I expect the difference to be significantly better AF and a higher frame rate in the 7D, with a few minor improvements... I would also expect NO articulated screen in the 7D2.

Time will tell. I have no intentions of getting a 70D, but since it's features will give a good clue to the 7D2, I eagerly await it's announcement.

I agree, the smart move would be to put the current 7D AF maybe tweeked a bit into the 70D it would essentiaqlly become the 7D low price replacement.

then give the 7D2 the 61 point AF and awesome build essentially put a new crop sensor into a 5Dmk3 10FPS?maybe 8FPS full raw and 10FPS jpg or something like that, depends what processing they give It esspecially if it gets more megapickles I doubt it would get 10FPS raw as thats getting closer to eating 1Dx lunch.

what canon ACTUALLY do might cause some head scrathing however based on current form it will be more in the 5Dmk3 price range but I can still see it selling tons